package com.lyeducation.util;

import java.security.MessageDigest;
import java.util.Arrays;


public class CheckUtil {

    public static final String tooken = "jredu100"; //开发者自行定义Tooken

    public static boolean checkSignature(String signature, String timestamp, String nonce) {

//1.定义数组存放tooken，timestamp,nonce

        String[] arr = {tooken, timestamp, nonce};

//2.对数组进行排序

        Arrays.sort(arr);

//3.生成字符串

        StringBuffer sb = new StringBuffer();

        for (String s : arr) {

            sb.append(s);

        }

//4.sha1加密,网上均有现成代码

        String temp = getSha1(sb.toString());

//5.将加密后的字符串，与微信传来的加密签名比较，返回结果

        return temp.equals(signature);

    }


    public static String getSha1(String str) {

        if (str == null || str.length() == 0) {

            return null;

        }

        char hexDigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',

                'a', 'b', 'c', 'd', 'e', 'f'};

        try {

            MessageDigest mdTemp = MessageDigest.getInstance("SHA1");

            mdTemp.update(str.getBytes("UTF-8"));


            byte[] md = mdTemp.digest();

            int j = md.length;

            char buf[] = new char[j * 2];

            int k = 0;

            for (int i = 0; i < j; i++) {

                byte byte0 = md[i];

                buf[k++] = hexDigits[byte0 >>> 4 & 0xf];

                buf[k++] = hexDigits[byte0 & 0xf];
 
            }

            return new String(buf);

        } catch (Exception e) {

            // TODO: handle exception

            return null;

        }

    }

}
